I discovered today that the translucent binder and pigments contain ammonia. For this reason, spare binder should not be kept in recycled plastic or glass containers. We use recycled food containers extensively to mix and store small quantities of binder. But we noticed that after a week or so, the plastic containers start to buckle slightly. Apparently if left for a month or so, the plastic will degrade and start to leak. Additionally if binder and pigment is kept in a glass jar, the ammonia makes the glass go brittle, and can break, particularly if pressure is applied when twisting off a lid that is jammed with dried muck.
When mixing binder at Herts, we buy plastic containers for about 50p each from the print shop. These have never buckled in use, so I suppose they are made from plastic designed to handle the ammonia. I've never thought of recycling plastic containers at Herts, probably because there is a shop on site, providing reasonably priced materials. It had not occurred to me that not every container is suitable for storage for print materials. The print shop is definitely an asset, because it provides reputable materials, at near to cost price. Cheap, convenient and quality control done for you. What more can you ask? Yet for some legislative reason, Australian universities are not allowed to run a shop.